JPH09148875A - Piezoelectric vibrator and manufacture therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of a sealing, to improve the reliablity at the time of a mounting, to utilize the connection part of the upper surface electrode and the lower surface electrode of a substrate as the terminal electrode at the time of the mounting and to miniaturize a piezoelectric vibrator. SOLUTION: A via hole 3 being filled with conductive material for connecting plural electrode patterns on the upper surface and the lower surface of a mother substrate 1 is formed in the separation part of each piezoelectric vibrator. Each piezoelecric element 4 is mounted on the upper surface electrode pattern 2. Next, an adhesive sheet 7 in which a heat resisance filler having a recessed part 8 storing each piezoelectric element 4 is mixed is press-fixed, a heat curing processing is performed for the sheet and the sheet is made into sealing material. Subsequently, the conductive material of the via hole 3 is divided between each piezoelectric vibrator and is separated so as to make the same surface as the substrate side surface of each piezoelectrie vibrator, and the piezoelectric vibrator is manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibrator having a structure suitable for surface mounting, which is formed by encapsulating a piezoelectric element with an insulating substrate and a cap body, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Piezoelectric vibrators used for piezoelectric resonators and piezoelectric filters are widely used in various communication devices including wireless telephones such as cordless phones and cellular phones, and in various electronic devices such as personal computers. ,
In particular, the surface-mounted piezoelectric vibrator is rapidly expanding its market in recent years as a small, lightweight, and space-saving electronic component.

The structure of such a surface mount type piezoelectric vibrator is one in which a piezoelectric element or the like is mounted on an insulating substrate, and a cap made of ceramic or metal is covered and adhesively sealed. It is common.

For example, in Japanese Patent Laid-Open No. 3-265204, electrodes are formed on the front and back main surfaces of a piezoelectric substrate,
An insulating protective substrate is placed on each of the two main surfaces through an adhesive sheet formed so as to have an opening in at least the vibrating portion area, and the upper and lower protective substrates are adhered to the piezoelectric substrate to surround the vibrating portion with an adhesive. A piezoelectric resonator component in which a sealed vibration space is formed by the thickness of the adhesive is disclosed. According to it, an adhesive layer having a uniform thickness can be obtained by using a thermosetting type of a semi-solid resin sheet such as an epoxy-based adhesive sheet, so that an adhesive layer can be applied or printed. The process is simplified and the productivity is improved and the cost is reduced as compared with the method of doing, and the accuracy of the thickness of the adhesive layer is high and it is less likely to entrap air bubbles or foreign matter, so it is advantageous. The quality of the piezoelectric resonator component is improved,
The reliability is improved. In addition, in the same publication, a plurality of components are simultaneously formed using a mother board,
A method of cutting into individual parts is also disclosed.

Further, in Japanese Patent Application Laid-Open No. 6-37565, an electronic component element such as a piezoelectric vibrator is sealed in a case consisting of a lower case and an upper lid with an adhesive sheet which has been molded in accordance with the shape of the lower case. A chip-type electronic component having a structure is disclosed. The adhesive sheet has a first adhesive that cures at a relatively low temperature on one side of the substrate, a second adhesive that cures at a relatively high temperature on the other side, and a second adhesive. The surface of the adhesive is covered with a protective sheet. Therefore, by bonding the adhesive sheet to the upper surface of the lower case when it is clean before applying the conductive paste, the adhesive sheet can be reliably bonded to the upper surface of the lower case without being affected by the conductive paste. In addition, since the conductive paste attached to the protective sheet can be easily and completely removed by peeling off the protective sheet, the upper lid can be reliably bonded on the adhesive sheet without being affected by the conductive paste. That is, it becomes a chip-type electronic component with high sealing performance.

Further, Japanese Patent Laid-Open No. 6-132766 discloses a base substrate, a piezoelectric ceramic element provided on the substrate, a terminal electrode electrically connected to the ceramic element and led to the outside, and a substrate. A piezoelectric oscillator having a conductive cap mounted on the ceramic substrate and covering the ceramic element, and an insulating plate interposed between the base substrate and the conductive cap is disclosed. By interposing this insulating plate, it is possible to prevent a short circuit of the terminal electrode due to the conductive cap (metal cap), and it is not necessary to bond the metal cap to the base substrate by fusion of the glass frit, so that the piezoelectric due to high temperature can be eliminated. It has the effect of suppressing the deterioration of the piezoelectric characteristics of the ceramic element.

Further, in Japanese Unexamined Patent Publication No. 7-170143, an insulating substrate having electrodes formed on the front and back sides through semicircular cutout side electrodes on the outer peripheral edge and a position facing the side electrodes of the insulating substrate on the outer surface are provided. There is disclosed a ceramic resonator in which a capacitive element arranged on an insulating substrate is hermetically fixed by a cap case having a groove formed therein. According to this, since the side electrode portion of the insulating substrate can be arranged in the groove space position of the cap case, the area of the insulating substrate can be reduced, and the insulating substrate having a size similar to that of the cap case can be commercialized. That is to say.

[0008]

However, in the piezoelectric resonator component disclosed in Japanese Unexamined Patent Publication No. 3-265204, an epoxy resin sheet used as an adhesive sheet is heated to a predetermined temperature (80 to 100 ° C.). Then it becomes liquefied and 150 more
Since it is hardened by keeping it at ~ 180 ° C for a certain period of time, when forming electrode patterns on the front and back of the mother board and connecting them with terminal electrodes formed with through holes, etc., liquefied epoxy will pass through. There is a problem in that it flows into the hole and does not function as a terminal electrode. Further, there is a problem that the air pressure in the vibrating space rises at the time of heat curing to cause blow-through, which easily causes parts having poor airtightness.

Further, the chip-type electronic component disclosed in Japanese Patent Laid-Open No. 6-37565 has a problem that the manufacturing cost becomes high because the adhesive sheet is expensive. Also,
Since the reaction of the second conductive paste progresses when the first adhesive or the conductive paste is cured, there is a problem that sealing is likely to be incomplete.

Further, in the piezoelectric oscillator disclosed in JP-A-6-132766 or the ceramic resonator disclosed in JP-A-7-170143, an epoxy adhesive is applied to the opening end surface of the cap and placed on a substrate for heating. In order to cure the adhesive, it is necessary to take a large board size so that the adhesive does not come into contact with the piezoelectric ceramic element or the capacitive element, and the adhesive does not flow out to the external terminal formation part and contaminate the terminal electrode surface. However, there is a problem that the component has a larger board occupying area than the elements housed inside. Further, it is necessary to form a terminal electrode for connecting the electrode patterns formed on the front and back of the substrate in a later step,
When the terminal electrode is formed by a through hole, there is also a problem that a liquefied adhesive flows in and the characteristics are deteriorated and a connection failure easily occurs. Further, there is a problem that the air pressure in the inner space of the cap rises at the time of heat curing, blow-through occurs, and parts having poor airtightness are likely to occur.

The present invention has been completed as a result of intensive research conducted by the present inventors in view of the above problems, and its purpose is to:
An object of the present invention is to provide a surface-mounted piezoelectric vibrator that does not have troubles such as resin flow of an adhesive at the time of sealing, characteristic deterioration and connection failure due to it, and does not require terminal electrode formation in a subsequent process. Another object of the present invention is to provide a surface-mounted piezoelectric vibrator that has a small number of components, can be downsized, does not cause blow-through, and has excellent sealing airtightness.

A further object of the present invention is to provide a method of manufacturing a surface-mounted piezoelectric vibrator, which has a small number of parts, can reduce the number of manufacturing steps, and can be easily managed during manufacturing processing. . Moreover, there is no trouble such as resin flow of the sealing adhesive, and when a plurality of piezoelectric vibrators are manufactured on the mother substrate, they can be surface-mounted immediately after being separated into individual piezoelectric vibrators. It is an object of the present invention to provide a method for manufacturing a surface-mounted piezoelectric vibrator that does not require a special terminal electrode forming step.

[0013]

The piezoelectric vibrator of the present invention comprises:
Piezoelectric vibration including a substrate to which electrode patterns formed on the upper and lower surfaces are connected by side electrodes, a piezoelectric element mounted on the electrode pattern on the upper surface, and a sealing member having a recess for accommodating the piezoelectric element. In the child, the side surface electrode is formed in the recess provided on the side surface of the substrate so as to be flush with the side surface of the substrate, and the sealing member is formed by mixing a heat resistant filler in a resin adhesive. It is characterized by that.

In the above piezoelectric vibrator, the sealing member is formed by mixing a heat-resistant filler made of an inorganic material or a heat-resistant resin in an epoxy resin-based resin adhesive.

The method of manufacturing the piezoelectric vibrator of the present invention is
Electrode patterns for a plurality of piezoelectric vibrators are provided on the upper and lower surfaces of the mother substrate, and via holes filled with a conductive material for connecting the electrode patterns on the respective upper and lower surfaces to the separated portions of each piezoelectric vibrator on the mother substrate. Each formed, each piezoelectric element is mounted on the electrode pattern on the upper surface, then, having a recess for accommodating each piezoelectric element, an adhesive sheet mixed with a heat-resistant filler is pressure-bonded to the mother substrate and subjected to thermosetting treatment, After forming the sealing member, the via holes are divided to separate the piezoelectric vibrators so that the conductive material is flush with the substrate side surface of each piezoelectric vibrator.

Further, in the above-mentioned method for manufacturing a piezoelectric vibrator, after the adhesive sheet is kneaded with a heat-resistant filler made of an inorganic material or a heat-resistant resin in each of the base material and the curing agent of the epoxy resin-based resin adhesive, It is formed by mixing the main agent and the curing agent.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a piezoelectric vibrator of the present invention and a method for manufacturing the same will be described in detail with reference to the drawings. The present invention is not limited to the following examples, and various modifications and improvements can be made without departing from the spirit of the present invention.

FIG. 1 is an exploded perspective view showing an example of a method for manufacturing a piezoelectric vibrator of the present invention.

In FIG. 1, reference numeral 1 is a mother substrate. The mother substrate 1 is made of an insulating material or a dielectric material such as ceramics, glass, alumina, a dielectric substrate, or a glass epoxy substrate, and is separated according to a cut line (separation portion) shown by a one-dot chain line in FIG. It becomes the substrate of the piezoelectric vibrator.

A predetermined electrode pattern 2 is formed on the upper surface of the mother substrate 1.
And a predetermined electrode pattern (not shown) on the lower surface,
It is formed by thick film printing and baking with copper (Cu), silver-palladium (Ag-Pd) paste, or the like.

In this example, elliptical via holes 3 are formed on the upper and lower surfaces of the electrode pattern 2 along the cut lines. The via hole 3 is filled with a conductive material such as silver (Ag) or a metal having a good solderability such as solder so as to penetrate the mother substrate 1 and connect the electrode patterns 2 on the upper surface and the lower surface. And
By separating along the cut line, the conductive material filled in the inside is divided, and the exposed surface is flush with the substrate side surface of each piezoelectric vibrator, and becomes a side surface electrode described later.

The size and position of the via hole 3 may be appropriately set in accordance with the required specifications of the electrode pattern and the side surface electrode for the piezoelectric vibrator, and the shape of each via hole 3 when separated into individual piezoelectric vibrators. In addition to the oval shape shown in the figure, electrode patterns, etc. can be used as long as they are side electrodes filled with a conductive material so as to be flush with the substrate side surface in the recess formed in the substrate side surface. Depending on the shape, the shape may be rectangular, square, diamond-shaped quadrilateral, circular, or any other shape.

To form the via hole 3, for example, a low temperature fired substrate tape to be the mother substrate 1 is opened by making an ellipse of about 0.5 mm × 1.0 mm as shown in FIG. A conductive material such as Ag paste is filled and integrally fired. Next, the electrode patterns 2 made of Ag-Pd or the like may be formed on the upper surface and the lower surface of the substrate tape by thick film printing or the like so as to be connected by the via holes 3. The formation order of the via hole 3 and the electrode pattern 2 may be reversed.

The via holes 3 are formed by firing the mother substrate 1 and printing Ag-Pd electrodes on the upper and lower surfaces by thick film to form the electrode pattern 2, and then forming an elliptical through hole on the inner surface. Similarly, an Ag-Pd electrode film may be attached, and after baking it, a conductive material such as solder may flow into the inside.

Reference numeral 4 is a piezoelectric element, and drive electrodes 5 are formed on both main surfaces of the piezoelectric element. The drive electrodes 5 are fixed and connected to the electrode pattern 2 on the upper surface by a conductive paste 6 and mounted on each piezoelectric vibrator. Has been done. In addition to the piezoelectric element 4, various circuit elements and circuit components can be mounted and formed to form various surface mount electronic components.

Reference numeral 7 denotes an adhesive sheet which serves as a sealing member for the piezoelectric vibrator of the present invention, and has a concave portion 8 for accommodating the piezoelectric element 4 of each piezoelectric vibrator on the side which is pressed against the mother substrate 1. doing. In addition, the dashed-dotted line shown on the adhesive sheet 7 in the figure is a cut line (separation part) corresponding to the above-mentioned cut line.

The adhesive sheet 7 is made by mixing a heat-resistant filler made of a ceramic such as alumina or an inorganic material such as glass or a heat-resistant resin such as PPS / crystallized polymer into an epoxy resin-based resin adhesive, It is formed from a solid kneaded clay-like material, which has a fluidity at the time of thermosetting to be suppressed so as not to lose its shape. As the mixing ratio of the heat-resistant filler, for example, when using silica sand,
Epoxy resin: silica sand = 1: 3 to 1: 9
Moldability is good, and thixotropy at the time of heat curing is high, which is preferable.

The epoxy resin-based resin adhesive used for the adhesive sheet 7 is a two-liquid mixed type which cures in about 12 hours by mixing the main agent and the curing agent. Are separately kneaded with the heat resistant filler in advance, and they are mixed and used immediately before forming into a sheet.

The size of the concave portion 8 is appropriately set according to the size of the piezoelectric element 4 and the gap required around it. To form the concave portion 8, one adhesive sheet may be formed by press forming or the like, or a two-sheet structure may be formed.
A sheet having a thickness corresponding to the depth of the concave portion 8 and a punched hole having the size of the concave portion 8 may be stacked and formed on a single sheet.

The adhesive sheet 7 thus formed is placed on the mother substrate 1, press-bonded, and then heat-cured to seal the piezoelectric element 4. When the mother substrate 1 is heated to about 50 to 80 ° C. during this press-bonding, the adhesion with the adhesive sheet 7 becomes good and excellent sealing and airtightness can be obtained. Then, this is left as it is for about 12 to 24 hours, and heat treatment is performed at about 150 ° C. for sealing.

FIG. 2 shows the state after this sealing, and AA is the state in which the mother substrate 1 and the adhesive sheet 7 shown in FIG.
It is shown in a line sectional perspective view. 2, the same parts as those in FIG. 1 are designated by the same reference numerals. Further, the alternate long and short dash line in FIG. 2 also indicates the cut line (separation portion). 9 in FIG.
Is an electrode pattern on the lower surface, and 10 is an electrode film formed on the inner wall of the via hole 3 together with the electrode patterns 2 and 9. The electrode film 10 does not necessarily have to be formed.

By separating along the cut lines shown in FIGS. 1 and 2 with a diamond wheel or a wire cut, individual piezoelectric vibrators 11 as shown in the external perspective view of FIG. 3 can be obtained. 12 is the mother board 1
Is a substrate separated from the above, 13 is a sealing member separated from the adhesive sheet 7, 14 is a lower surface electrode pattern obtained by dividing the lower surface electrode pattern 9, and 15 is a side surface formed by dividing the via hole 3. It is an electrode. The side electrode 15 connects the electrode pattern 14 on the lower surface and the electrode pattern (not shown) on the upper surface.

In the piezoelectric vibrator 11 thus manufactured, the via holes 3 are separated so as to be divided along the cut line as described above, so that the side surface of the substrate 12 to be a separation surface is formed on that side surface. The conductive material filled in the via hole 3 is exposed in the recess thus formed so that the exposed surface is flush with the side surface of the substrate 12, and the side electrode 15 of the piezoelectric vibrator 11 is formed. The piezoelectric vibrator 11 can be surface-mounted as it is by solder reflow or the like without needing to form electrodes. Moreover, since the conductive material is filled in the recess formed in the substrate 12, the sealing width does not become narrower by the recess when sealing, and the sealing reliability is excellent. It becomes a thing.

Further, by sealing with the adhesive sheet 7 as the sealing member as described above, the adhesive sheet 7 molded as described above has a proper flexibility in a semi-cured state. Therefore, even if there is variation in the shape of the piezoelectric element 4 fixing portion on the mother substrate 1 due to, for example, a conductive paste flowing or highly adhering like a horn, the variation and the defective portion due to it are absorbed. can do. Therefore, even if the gap around the piezoelectric element 4 is set to a minimum (about 0.1 mm), the vibration of the piezoelectric element 4 is not damped, and a small-sized piezoelectric vibrator having stable characteristics can be obtained. it can.

Further, even when the adhesive sheet 7 is thermally cured, the sealing portion with the substrate is pressed by the hard adhesive, so that blow-through does not occur, and the sealing is prevented. It is possible to obtain a piezoelectric vibrator having excellent airtightness.

Moreover, since the adhesive sheet 7 is mixed with a filler to suppress the fluidity of the adhesive resin, the adhesive resin does not adhere to the piezoelectric element 4 to cause damping. Further, since the upper and lower electrode patterns 2 and 9 are connected by the via holes 3, the adhesive resin does not flow into the connecting portions, and the via holes 3
By separating the individual piezoelectric vibrators so as to divide into, the side electrodes 15 on the side surfaces of the substrate 12 can be immediately formed. Therefore, there is no need to consider the outflow / inflow of the adhesive resin, and the management of the manufacturing process becomes easy.

As described above, according to the piezoelectric vibrator 11 of the present invention, the side surface electrode 15 formed by filling the concave portion with the conductive material having good solderability is formed on the side surface of the substrate 12, so that mounting is performed. Since the solder or the like creeps up the side surface electrode 15 during the solder mounting on the board, it is possible to easily confirm whether or not the soldering is reliably performed, and it is possible to improve the mounting strength on the mounting board. Further, surface mounting using the side electrode 15 can be performed.

Further, according to the method for manufacturing a piezoelectric vibrator of the present invention, the piezoelectric material filled in the via hole 3 is divided so that it is flush with the side surface of the substrate 12 of each piezoelectric vibrator 11. Since the vibrators 11 are separated from each other, the divided via holes 3 form the side electrodes 15 on the substrate 12 of each piezoelectric vibrator 11. Therefore, it is possible to manufacture inexpensively without a step of newly forming electrodes for connecting the upper and lower electrode patterns to the separated piezoelectric vibrator 11, and the side electrode 15 as described above is formed. A highly reliable surface mount piezoelectric vibrator 11 capable of performing various surface mounts is obtained.

[0039]

As described in detail above, according to the piezoelectric vibrator of the present invention, the side surface electrode is formed in the concave portion provided on the side surface of the substrate such that the exposed surface thereof is flush with the side surface of the substrate. In addition, by using a resin adhesive with a heat-resistant filler mixed in it as a sealing member after curing, there are no problems such as resin flow of the adhesive during sealing, and there is no characteristic deterioration or connection failure due to it. As a result, it is possible to provide a surface-mounted piezoelectric vibrator that does not require the formation of terminal electrodes in the subsequent process.

Further, when sealing, the sealing width does not become narrower by the amount of the concave portion, the sealing reliability is excellent, and the surface mounting type piezoelectric vibration occupying a small area on the mounting substrate. I was able to provide a child. Furthermore, it was possible to provide a surface-mounted piezoelectric vibrator that has a small number of parts, can be downsized, does not cause blow-through, and has excellent sealing airtightness. Then, since solder for mounting and the like creeps up the side electrodes, it is possible to easily confirm the soldering and improve the mounting strength to the mounting board, and it is possible to easily support various surface mountings. Could be provided.

Further, according to the method of manufacturing a piezoelectric vibrator of the present invention, via holes filled with a conductive material for connecting the electrode patterns on the upper surface and the lower surface of the respective piezoelectric vibrators on the mother substrate are respectively formed. After the adhesive sheet containing the heat-resistant filler is pressure-bonded to the mother substrate to form a sealing member by thermosetting, the via holes are divided and the conductive material is separated from the substrate side surface of each piezoelectric vibrator. By separating the piezoelectric vibrators so that they are on the same plane, the number of parts is small and the number of manufacturing processes can be reduced. Surface mount type piezoelectric vibration that is easy to manage during manufacturing processing. It was possible to provide a method for manufacturing a child.

When there are no troubles such as resin flow of the sealing adhesive and a plurality of piezoelectric vibrators are produced on the mother substrate, the piezoelectric vibrations can be immediately surface-mounted by separating them into individual piezoelectric vibrators. As a child, it was possible to provide a method for manufacturing a surface-mounted piezoelectric vibrator that requires no special terminal electrode forming step.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an example of a method for manufacturing a piezoelectric vibrator of the present invention.

FIG. 2 is a cross-sectional view corresponding to the cross-sectional view taken along the line AA of FIG.

FIG. 3 is an external perspective view showing an example of the piezoelectric vibrator of the present invention.

[Explanation of symbols]

1 ... Mother substrate, 2 ... Electrode pattern on top surface, 3 ...
・ Via hole, 4 ... Piezoelectric element, 7 ... Adhesive sheet, 8 ... Recessed portion, 9, 14 ... Electrode pattern on bottom surface,
11 ... Piezoelectric vibrator, 12 ... Substrate, 13 ... Sealing member (adhesive sheet), 15 ... Side electrode

Claims (4)

[Claims] 1. A sealing member having a substrate to which electrode patterns formed on an upper surface and a lower surface are connected by side surface electrodes, a piezoelectric element mounted on the electrode pattern on the upper surface, and a recess for accommodating the piezoelectric element. In the piezoelectric vibrator, the side electrode is formed in the recess provided on the side surface of the substrate so as to be flush with the side surface of the substrate, and the sealing member is a heat-resistant filler in a resin adhesive. A piezoelectric vibrator characterized by being mixed with. 2. The piezoelectric vibrator according to claim 1, wherein the sealing member is formed by mixing a heat-resistant filler made of an inorganic material or a heat-resistant resin in an epoxy resin-based resin adhesive. 3. A conductive material for connecting a plurality of electrode patterns for piezoelectric vibrators on the upper surface and the lower surface of a mother substrate, and connecting the electrode patterns on the upper surface and the lower surface of each to the separating portion of each piezoelectric vibrator of the mother substrate. Via holes filled with the respective piezoelectric elements are mounted on the electrode pattern on the upper surface, and then an adhesive sheet containing a heat-resistant filler is recessed on the mother substrate, the adhesive sheet having recesses for accommodating the piezoelectric elements. After the thermosetting treatment and forming the sealing member, the via holes are divided to separate the piezoelectric vibrators so that the conductive material is flush with the substrate side surface of each piezoelectric vibrator. Piezoelectric vibrator manufacturing method. 4. The adhesive sheet is prepared by kneading a heat-resistant filler made of an inorganic material or a heat-resistant resin with each of a main agent and a curing agent of an epoxy resin-based resin adhesive, and then mixing the main agent and the curing agent. The method for manufacturing a piezoelectric vibrator according to claim 3, wherein the piezoelectric vibrator is formed by molding.